The present invention relates generally to active phased array antenna arrays for generating communications signals. More specifically, but without limitation thereto, the present invention relates to shifting the phase of an input signal at each array element of an antenna to form a beam.
A phased array antenna is typically used for transmitting and receiving microwave signals in a specific beam direction or multiple directions at the same time. The array elements of the phased array antenna consist of a large number of radiators. In the receiving mode, the signal from each array element is phase shifted or time shifted (for large bandwidth signals) by a chain of phase shifters before summing to generate a beam output signal. The networks of phase shifter chains currently used for phased array antennas are typically large and have a correspondingly high cost.
The present invention advantageously addresses the problems above as well as other problems by providing a phase control network for combining signals from a phased array antenna having a substantially reduced number of components.
In one embodiment, the present invention may be characterized as a phase control block for combining signals from a phased array antenna that includes a phase shifter for generating a phase shifted signal; a phase switch connected to the phase shifter having a first state wherein the phase switch connects a first signal to a switched signal output and a second signal to the phase shifter; and a signal summing device connected to the phase shifter for generating an output that is a sum of the switched signal output and the phase shifted signal.
In another embodiment, the present invention may be characterized as a phase control network for combining signals from a phased array antenna that includes a plurality of phase control blocks having a pair of inputs and a single output connected in a tree pattern to generate a single beam output signal.
In yet another embodiment, the present invention may be characterized as a method for combining signals from a phased array antenna that includes the steps of (a) receiving a plurality of input signals in pairs wherein each of the pairs comprises a first input signal and a second input signal; (b) phase shifting one of the first input signal and the second input signal to generate a phase-shifted signal; and (c) summing the phase shifted signal with another of the first input signal and the second input signal to generate a sum signal for each of the pairs.